Voltage detection device

ABSTRACT

To provide voltage detection device capable of reducing variations and errors in detection voltage caused by influence of configuration of pattern wiring and temperature when detecting voltages applied to a plurality of resistance elements connected in parallel. Voltage detection device includes resistance unit including a plurality of resistance elements connected in parallel, differential amplifier circuit, first connection portion having two wiring portions connecting positions different from each other in one end portion of resistance unit and input terminal of differential amplifier circuit, and second connection portion having two wiring portion connecting positions different from each other in other end portion of resistance unit and input terminal of differential amplifier circuit. Voltage detection device configures to detect voltage applied to resistance unit based on voltage of output terminal of differential amplifier circuit.

TECHNICAL FIELD

The present invention relates to a voltage detection device that detectsvoltages applied to a plurality of resistance elements connected inparallel.

BACKGROUND ART

When a current flowing through a switching power supply or the like isdetected, a voltage is first detected, and then a current is calculatedfrom the detected voltage. For example, a resistance element is disposedin an output portion of a switching power supply or the like, and avoltage applied to the resistance element is detected.

A large current may flow through the resistance element. In this case,the voltage applied to the resistance element increases. It is notpreferable that a large current or a large voltage is applied to theresistance element. Therefore, a plurality of resistance elements areconnected in parallel. As a result, the current flows separately in eachresistance element, so that the current flowing in one resistanceelement can be suppressed to be small. In addition, since the combinedresistance value of the plurality of resistance elements connected inparallel becomes small, the voltage applied to the plurality ofresistance elements connected in parallel can be suppressed to be small.For example, Patent Document 1 discloses a voltage detection devicecapable of detecting a voltage applied to a circuit in which a pluralityof resistance elements are connected in parallel.

PRIOR ART DOCUMENT Patent Document

-   Patent Document 1: Japanese Patent Laid-open Publication No.    2013-255340

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

However, when the voltage applied to the resistance elements connectedin parallel is detected, the following problem may occur.

When the resistance elements connected in parallel are mounted on asubstrate, the resistance elements are connected by a pattern wiringmade of copper or the like. There are various configurations of such asa width, a length, and a path of the pattern wiring.

When the configuration of the pattern wiring connecting the resistanceelements is different, the current may not uniformly flow to theplurality of resistance elements and may flow unevenly to a specificresistance element. In this case, the detected voltage varies dependingon the position in the pattern wiring where the voltage is detected.

In addition, impedance is generated in the pattern wiring. Thisimpedance changes the combined resistance value of the plurality ofresistance elements connected in parallel. As a result, an error occursin the detected voltage. The larger the generated impedance, the largerthe error. For example, when the pattern wiring connecting tworesistance elements becomes long, the impedance generated between thetwo resistance elements becomes large. The impedance of the patternwiring varies depending on the temperature. The higher the temperature,the larger the generated impedance.

Therefore, an object of the present invention is to solve the aboveproblems, and to provide a voltage detection device capable of reducingvariations and errors in detection voltage caused by the influence ofthe configuration of a pattern wiring and temperature when detectingvoltages applied to a plurality of resistance elements connected inparallel.

Means for Solving the Problems

In order to achieve the above object, the present invention isconfigured as follows.

A voltage detection device according to one aspect of the presentinvention includes:

-   -   a resistance unit including a plurality of resistance elements        connected in parallel;    -   a differential amplifier circuit;    -   a first connection portion that connects a plurality of        positions different from each other in one end portion of the        resistance unit and a first input terminal of the differential        amplifier circuit; and    -   a second connection portion that connects a plurality of        positions different from each other in the other end portion of        the resistance unit and a second input terminal of the        differential amplifier circuit,    -   wherein the voltage detection device configures to detect a        voltage applied to the resistance unit based on a voltage of an        output terminal of the differential amplifier circuit.

Effects of the Invention

According to the present invention, it is possible to reduce variationsand errors in detection voltage caused by the influence of theconfiguration of a pattern wiring and temperature when detecting thevoltages applied to the plurality of resistance elements connected inparallel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a circuit diagram of a voltage detection device according to afirst embodiment of the present invention.

FIG. 2 is a circuit diagram of the voltage detection device according tothe first embodiment of the present invention used for simulation.

FIG. 3 is a circuit diagram of a voltage detection device according to aconventional mode used for simulation.

FIG. 4 is a table showing simulation results according to the firstembodiment.

FIG. 5 is a graph showing the simulation results of the firstembodiment.

FIG. 6 is a circuit diagram of a voltage detection device according to asecond embodiment of the present invention.

FIG. 7 is a table showing simulation results of the second embodiment.

FIG. 8 is a graph showing the simulation results of the secondembodiment.

FIG. 9 is a circuit diagram of a voltage detection device according to athird embodiment of the present invention.

MODES FOR CARRYING OUT THE INVENTION

A voltage detection device according to one aspect of the presentinvention includes:

-   -   a resistance unit including a plurality of resistance elements        connected in parallel;    -   a differential amplifier circuit;    -   a first connection portion that connects a plurality of        positions different from each other in one end portion of the        resistance unit and a first input terminal of the differential        amplifier circuit; and    -   a second connection portion that connects a plurality of        positions different from each other in the other end portion of        the resistance unit and a second input terminal of the        differential amplifier circuit,    -   wherein the voltage detection device configures to detect a        voltage applied to the resistance unit based on a voltage of an        output terminal of the differential amplifier circuit.

According to this configuration, the one end portion of the resistanceunit and the differential amplifier circuit are connected by theplurality of wirings. As a result, it is possible to detect a voltage inwhich the influence of the configuration of the wiring pattern of theresistance unit and the temperature is suppressed to be low.

The first connection portion includes:

-   -   a first wiring portion that connects one end of a first        resistance element, which is one of the first resistance element        and a second resistance element located at positions farthest        from each other among the plurality of resistance elements of        the resistance unit, and the first input terminal; and    -   a second wiring portion that connects one end of the second        resistance element and the first input terminal, and    -   the second connection portion includes:    -   a third wiring portion that connects the other end of the first        resistance element and the second input terminal; and    -   a fourth wiring portion connecting the other end of the second        resistance element and the second input terminal.

According to this configuration, the first wiring portion and the thirdwiring portion extend from the first resistance element, and the secondwiring portion and the fourth wiring portion extend from the secondresistance element. Here, the first resistance element and the secondresistance element are two resistance elements farthest from each otheramong the plurality of resistance elements. In such a configuration, theinfluence of the wiring pattern can be suppressed to be lower than in aconfiguration in which two resistance elements to which the wiringportions are connected are located closer to each other, and thus, theinfluence of uneven current flow due to the difference in theconfiguration of the pattern wiring connecting the resistance elementscan be reduced.

The first connection portion may connect one end of each of theplurality of resistance elements and the first input terminal, and

-   -   the second connection portion may connect the other end of each        of the plurality of resistance elements and the second input        terminal.

According to this configuration, the wiring portions extend from all theresistance elements of the resistance unit. In such a configuration, itis possible to detect a voltage in which the influence of theconfiguration of the wiring pattern of the resistance unit and thetemperature is suppressed to be lower than in a configuration in whichthe wiring portion extends from some resistance elements among theplurality of resistance elements included in the resistance unit.

One ends of the plurality of resistance elements are connected in astate of being aligned in a first direction at the one end portion ofthe resistance unit,

-   -   a plurality of positions of the first connection portion are        located at equal intervals in the first direction,    -   the other ends of the plurality of resistance elements are        connected in a state of being aligned in a second direction at        the other end portion of the resistance unit, and    -   a plurality of positions of the second connection portion may be        located at equal intervals in the second direction.

Also with this configuration, the one end portion and the other endportion of the resistance unit are connected to the differentialamplifier circuit by the plurality of wirings. As a result, it ispossible to detect a voltage in which the influence of the configurationof the wiring pattern of the resistance unit and the temperature issuppressed to be low.

First Embodiment

FIG. 1 is a circuit diagram of a voltage detection device according to afirst embodiment of the present invention.

A voltage detection device 10 is connected to an external device. Thevoltage detection device 10 of the first embodiment is connected to anoutput unit 71 of a switching power supply 70 as an example of anexternal device. The voltage detection device 10 can detect a voltageapplied to a resistance unit 20 included in the voltage detection device10. Based on the resistance value of the resistance unit 20 and thedetected voltage, a current flowing through the output unit can becalculated by Ohm's law.

As illustrated in FIG. 1 , the voltage detection device 10 includes theresistance unit 20, a first connection portion 30, a second connectionportion 40, and a differential amplifier circuit 50.

The resistance unit 20 is a circuit in which seven resistance elementsR1 to R7 are connected in parallel. The resistance value of each of theresistance elements R1 to R7 is 30 mΩ. The resistance value of each ofthe resistance elements R1 to R7 is not limited to 30 mΩ. The resistancevalues of the resistance elements R1 to R7 may be equal to each other asdescribed above or may be different from each other. In addition, thenumber of resistance elements included in the resistance unit 20 is notlimited to seven.

An input wiring 21 and an output wiring 22 are connected to theresistance unit 20.

One end portion 21A of the input wiring 21 is connected to one end R4Aof a resistance element R4 in one end portion 20A of the resistance unit20. The one end portion 20A of the resistance unit 20 is an end portionon one side (switching power supply side) of the resistance elements R1to R7 connected in parallel, and is a portion indicated by a thick linein FIG. 1 .

The other end portion 21B of the input wiring 21 is connected to, forexample, the output unit 71 of the switching power supply 70.

The one end portion 22A of the output wiring 22 is connected to theother end R4B of the resistance element R4 in the other end portion 20Bof the resistance unit 20. The other end portion 20B of the resistanceunit 20 is an end portion on the other side (opposite side to theswitching power supply) of the resistance elements R1 to R7 connected inparallel, and is a portion indicated by a thick line in FIG. 1 .

The other end portion 22B of the output wiring 22 is connected to, forexample, an external device 80 to which power is supplied by theswitching power supply 70.

Note that the input wiring 21 and the output wiring 22 may be connectedto other than the resistance element R4 among the resistance elements R1to R7. In addition, the resistance element to which the input wiring 21is connected and the resistance element to which the output wiring 22 isconnected may be different resistance elements. For example, the one endportion 21A of the input wiring 21 may be connected to one end R1A ofthe resistance element R1 in the one end portion 20A of the resistanceunit 20, and the one end portion 22A of the output wiring 22 may beconnected to the other end R7B of the resistance element R7 in the otherend portion 20B of the resistance unit 20.

The first connection portion 30 includes two wiring portions 31 and 32.The wiring portion 31 is an example of a first wiring portion. Thewiring portion 32 is an example of a second wiring portion.

One end portion 31A of the wiring portion 31 is connected to the one endR1A of the resistance element R1 in the one end portion 20A of theresistance unit 20. The other end portion 31B of the wiring portion 31is connected to an input terminal 50A of the differential amplifiercircuit 50. In this case, the input terminal 50A corresponds to a firstinput terminal.

A resistance element R31 is disposed in the wiring portion 31. Theresistance value of the resistance element R31 is 1Ω. The resistancevalue of the resistance element R31 is not limited to 1Ω.

One end portion 32A of the wiring portion 32 is connected to one end R7Aof the resistance element R7 in the one end portion 20A of theresistance unit 20. The other end portion 32B of the wiring portion 32is connected to the input terminal 50A of the differential amplifiercircuit 50.

A resistance element R32 is disposed in the wiring portion 32. Theresistance value of the resistance element R32 is 1Ω. The resistancevalue of the resistance element R32 is not limited to 1Ω. The resistancevalue of the resistance element R32 may be the same as or different fromthe resistance value of the resistance element R31.

The second connection portion 40 includes two wiring portions 41 and 42.The wiring portion 41 is an example of a third wiring portion. Thewiring portion 42 is an example of a fourth wiring portion.

One end portion 41A of the wiring portion 41 is connected to the otherend R1B of the resistance element R1 in the other end portion 20B of theresistance unit 20. The other end portion 41B of the wiring portion 41is connected to an input terminal 50B of the differential amplifiercircuit 50. In this case, the input terminal 50B corresponds to a secondinput terminal.

A resistance element R41 is disposed in the wiring portion 41. Theresistance value of the resistance element R41 is 1Ω. The resistancevalue of the resistance element R41 is not limited to 1Ω.

One end portion 42A of the wiring portion 42 is connected to the otherend R7B of the resistance element R7 in the other end portion 20B of theresistance unit 20. The other end portion 42B of the wiring portion 42is connected to the input terminal 50B of the differential amplifiercircuit 50.

A resistance element R42 is disposed in the wiring portion 42. Theresistance value of the resistance element R42 is 1Ω. The resistancevalue of the resistance element R42 is not limited to 1Ω. The resistancevalue of the resistance element R42 may be the same as or different fromthe resistance value of the resistance element R41. The resistancevalues of the resistance elements R41 and R42 may be the same as ordifferent from the resistance values of the resistance elements R31 andR32 of the wiring portion 41.

The resistance element R1 and the resistance element R7 are at positionsfarthest from each other among the seven resistance elements R1 to R7included in the resistance unit 20. That is, in the first embodiment,the wiring portions 31 and 41 are connected to the one end R1A and theother end R1B of one (resistance element R1) of the two resistanceelements R1 and R7 at the positions farthest from each other among theseven resistance elements R1 to R7 included in the resistance unit 20.On the other hand, the wiring portions 32 and 42 are connected to theone end R7A and the other end R7B of the other (resistance element R7)of the two resistance elements R1 and R7 at the positions farthest fromeach other among the seven resistance elements R1 to R7 included in theresistance unit 20. The resistance element R1 is an example of a firstresistance element. The resistance element R2 is an example of a secondresistance element.

On the condition that the connection positions of the wiring portions 31and 32 to the one end portion 20A of the resistance unit 20 aredifferent from each other, the connection positions of the wiringportions 31 and 32 to the one end portion 20A of the resistance unit 20are not limited to the one end R1A of the resistance element R1 and theone end R7A of the resistance element R7. For example, the wiringportion 31 may be connected to the one end R4A of the resistance elementR4, and the wiring portion 32 may be connected to one end R5A of theresistance element R5. That is, the two resistance elements to which thewiring portions 31 and 32 are connected may not be at the positionsfarthest from each other among the seven resistance elements R1 to R7included in the resistance unit 20. In addition, for example, the wiringportions 31 and 32 may be connected to a position between two adjacentresistance elements in the one end portion 20A of the resistance unit20. That is, the connection positions of the wiring portions 31 and 32to the one end portion 20A of the resistance unit 20 are not limited toone ends of the resistance elements R1 to R7.

Similarly, on the condition that the connection positions of the wiringportions 31 and 32 to the other end portion 20B of the resistance unit20 are different from each other, the connection positions of the wiringportions 41 and 42 to the other end portion 20B of the resistance unit20 are not limited to the other end R1B of the resistance element R1 andthe other end R7B of the resistance element R7.

A known configuration is adopted for the differential amplifier circuit50. As described above, the input terminal 50A of the differentialamplifier circuit 50 is connected to the wiring portions 31 and 32 ofthe first connection portion 30, and the input terminal 50B of thedifferential amplifier circuit 50 is connected to the wiring portions 41and 42 of the second connection portion 40. In the first embodiment, anoutput terminal 50C of the differential amplifier circuit 50 isconnected to a calculation unit 91. The calculation unit 91 includes acentral processing unit (CPU), a memory, and the like. The calculationunit 91 calculates a value of a current flowing through the resistanceunit 20 from the voltage value of the output terminal 50C of thedifferential amplifier circuit 50 and outputs the current value. Thecalculation unit 91 is connected to a display unit 92. In the firstembodiment, the display unit 92 is a known display including a pluralityof LEDs, liquid crystals, and the like. The current value output fromthe calculation unit 91 is input to the display unit 92. The displayunit 92 displays the input current value in a form (for example, anumber) that can be recognized by a user.

In the above description, the voltage value of the output terminal 50Cof the differential amplifier circuit 50 is converted into a currentvalue in the calculation unit 91, and the display unit 92 displays thecurrent value. However, the display unit 92 may display the voltagevalue of the output terminal 50C of the differential amplifier circuit50. In this case, the output terminal 50C of the differential amplifiercircuit 50 may be connected to the display unit 92 without passingthrough the calculation unit 91.

The differential amplifier circuit 50 includes an operational amplifier51 and resistance elements R51, R52, R53, and R54.

As the operational amplifier 51, a known one is used.

The gain of the differential amplifier circuit 50 is a ratio between aninput voltage (difference between the voltage of the input terminal 50Band the voltage of the input terminal 50A) and an output voltage(voltage of the output terminal 50C). In the differential amplifiercircuit 50, the resistance values of the resistance element R51 and theresistance element R52 are equal, the resistance values of theresistance element R53 and the resistance element R54 are equal, and thegain of the differential amplifier circuit 50 is R54/R51. In the firstembodiment, the resistance elements R51 and R52 are 1 kΩ. The resistanceelements R53 and R54 are 100 kΩ. That is, in the first embodiment, thegain of the differential amplifier circuit 50 is 100. The resistancevalues of the resistance elements R51 and R52 are not limited to 1 kΩ,and the resistance values of the resistance elements R53 and R54 are notlimited to 100 kΩ. That is, the gain of the differential amplifiercircuit 50 is not limited to 100.

The resistance values of the resistance elements R51 and R52 are set tobe extremely larger than the resistance values of the resistanceelements R31 and R32 of the first connection portion 30 and theresistance elements R41 and R42 of the second connection portion 40. Inother words, the resistance values of the resistance elements R31 andR32 of the first connection portion 30 and the resistance elements R41and R42 of the second connection portion 40 are set to be extremelysmaller than the resistance values of the resistance elements R51 andR52 to such an extent that the operation of the differential amplifiercircuit 50 is not affected. In the first embodiment, the resistancevalues (1 kΩ) of the resistance elements R51 and R52 are set to 1000times the resistance values (1Ω) of the resistance elements R31, R32,R41, and R42. The resistance values of the resistance elements R51 andR52 may be a magnification other than 1000 times the resistance valuesof the resistance elements R31, R32, R41, and R42.

The resistance element R51 is disposed on a wiring connecting the inputterminal 50A of the differential amplifier circuit 50 and an invertinginput terminal 51A of the operational amplifier 51. The resistanceelement R52 is disposed on a wiring connecting the input terminal 50B ofthe differential amplifier circuit 50 and a non-inverting input terminal51B of the operational amplifier 51. The resistance element R53 isdisposed on a wiring connecting the connection point 52 and the ground.The connection point 52 is located on the wiring between the resistanceelement R52 and the non-inverting input terminal 51B of the operationalamplifier 51. The resistance element R54 is disposed between theconnection point 53 and the connection point 54. The connection point 53is located on the wiring between the resistance element R51 and theinverting input terminal 51A of the operational amplifier 51. Theconnection point 54 is located on the wiring between an output terminal51C of the operational amplifier 51 and the output terminal 50C of thedifferential amplifier circuit 50.

In the above description, the configuration of the voltage detectiondevice 10 has been described on the basis of the circuit diagramillustrated in FIG. 1 . However, in practice, the voltage detectiondevice 10 is configured by mounting elements such as a resistanceelement and an operational amplifier on a substrate. In addition, theelements are connected by a pattern wiring made of copper or the like.That is, the wirings such as the one end portion 20A and the other endportion 20B of the resistance unit 20 illustrated in FIG. 1 are patternwirings made of copper or the like. For example, in the abovedescription, “connected to the one end R1A of the resistance element R1”includes not only being connected to the one end R1A of the resistanceelement R1 but also being connected to the pattern wiring located in thevicinity of the one end R1A of the resistance element Rt. Furthermore,for example, in the above description, “connected to a position betweentwo adjacent resistance elements in the one end portion 20A of theresistance unit 20” means being connected to a pattern wiring connectingthe two resistance elements.

FIG. 2 is a circuit diagram of the voltage detection device according tothe first embodiment of the present invention used for simulation. FIG.3 is a circuit diagram of a voltage detection device according to aconventional mode used for simulation.

Hereinafter, simulation results of voltage detection between the voltagedetection device 10 (voltage detection device illustrated in FIG. 2 )according to the first embodiment of the present invention and a voltagedetection device 100 (voltage detection device illustrated in FIG. 3 )according to the conventional mode will be described.

The voltage detection device 10 illustrated in FIG. 2 has substantiallythe same configuration as the voltage detection device 10 illustrated inFIG. 1 but differs in the following points.

In the voltage detection device 10 illustrated in FIG. 2 , theresistance elements included in the resistance unit 20 are fourresistance elements R1 to R4. In the resistance unit 20, resistanceelements Rp1 to Rp6 are disposed between two adjacent resistanceelements. The resistance elements Rp1 to Rp6 indicate impedancesgenerated in pattern wirings (the one end portion 20A and the other endportion 20B) constituting the resistance unit 20. For example, theresistance element Rp1 indicates impedance generated in the patternwiring existing between the adjacent resistance elements R1 and R2 amongthe pattern wirings constituting the one end portion 20A. The sameapplies to the resistance elements Rp2 and Rp3. In addition, forexample, the resistance element Rp4 indicates impedance generated in thepattern wiring existing between the adjacent resistance elements R1 andR2 among the pattern wirings constituting the other end portion 20B. Thesame applies to the resistance elements Rp5 and Rp6.

In the voltage detection device 10 illustrated in FIG. 2 , the one endportion 31A of the wiring portion 31 is connected to the one end R1A ofthe resistance element R1. The one end portion 32A of the wiring portion32 is connected to the one end R4A of the resistance element R4. Theother end portions 31B and 32B of the wiring portions 31 and 32 areconnected to the input terminal 50B of the differential amplifiercircuit 50. In this case, the input terminal 50B corresponds to thefirst input terminal. The one end portion 41A of the wiring portion 41is connected to the other end R1B of the resistance element R1. The oneend portion 42A of the wiring portion 42 is connected to the other endR4B of the resistance element R4. The other end portions 41B and 42B ofthe wiring portions 41 and 42 are connected to the input terminal 50A ofthe differential amplifier circuit 50. In this case, the input terminal50A corresponds to the second input terminal.

The voltage detection device 100 illustrated in FIG. 3 is different fromthe voltage detection device 10 illustrated in FIG. 2 in the followingpoints.

In the voltage detection device 100 illustrated in FIG. 3 , the firstconnection portion 30 and the second connection portion 40 include onlyone wiring portion. The first connection portion 30 includes the wiringportion 31 but does not include the wiring portion 32, and the secondconnection portion 40 includes the wiring portion 41 but does notinclude the wiring portion 42.

In the voltage detection device 100 illustrated in FIG. 3 , the one endportion 31A of the wiring portion 31 is connected to one end R3A of theresistance element R3. The resistance element R31 is not disposed in thewiring portion 31. The one end portion 41A of the wiring portion 41 isconnected to the other end R3B of the resistance element R3. Theresistance element R41 is not disposed in the wiring portion 41.

In the voltage detection device 10 illustrated in FIG. 2 and the voltagedetection device 100 illustrated in FIG. 3 , the other end portion 21Bof the input wiring 21 is connected to the power supply 60. The powersupply 60 represents an external device such as a switching power supplyin a pseudo manner. The other end portion 22B of the output wiring 22 ofthe voltage detection device 10 is connected to the ground. The groundrepresents an external device different from the switching power supplyin a pseudo manner. The output terminal 50C of the differentialamplifier circuit 50 is connected to the ground via a resistance elementR55.

In the simulation, a current of 1 A was passed from the power supply 60to each of the voltage detection devices 10 and 100, and the voltage atthe output terminal 50C of the differential amplifier circuit 50 of eachof the voltage detection devices 10 and 100 at that time was measured.The simulation was performed for each case where the temperature aroundeach of the voltage detection devices 10 and 100 was 0° C., 50° C., and100° C. In the simulation, the difference in temperature was representedby the difference in resistance values of the resistance elements Rp1 toRp6. That is, the resistance values of the resistance elements Rp1 toRp6 at the respective temperatures were set based on the fact that thehigher the temperature, the larger the impedance generated in thepattern wiring. In the simulation, the resistance values of theresistance elements Rp1 to Rp6 at a temperature of 0° C. were set to 1.5mΩ, the resistance values of the resistance elements Rp1 to Rp6 at atemperature of 50° C. were set to 1.89 mΩ, and the resistance values ofthe resistance elements Rp1 to Rp6 at a temperature of 100° C. were setto 2.23 mΩ.

The results of the simulation are shown in FIG. 4 and FIG. 5 . FIG. 4 isa table showing simulation results according to the first embodiment.FIG. 5 is a graph showing the simulation results of the firstembodiment.

FIG. 4 and FIG. 5 show the voltage value of the output terminal 50C ofthe differential amplifier circuit 50 in the voltage detection device 10illustrated in FIG. 2 , the voltage value of the output terminal 50C ofthe differential amplifier circuit 50 in the voltage detection device100 illustrated in FIG. 3 , and the ideal voltage value of the outputterminal 50C of the differential amplifier circuit 50 for eachtemperature of 0° C., 50° C., and 100° C. The ideal voltage value is avoltage value of the output terminal 50C of the differential amplifiercircuit 50 when the resistance elements Rp1 to Rp6 do not exist.

As shown in FIG. 4 and FIG. 5 , the ideal voltage value is 750 mVregardless of the temperature. That is, in both the voltage detectiondevice 10 illustrated in FIG. 2 and the voltage detection device 100illustrated in FIG. 3 , when the resistance elements Rp1 to Rp6 do notexist, the voltage value of the output terminal 50C of the differentialamplifier circuit 50 is 750 mV.

In the voltage detection device 100 (voltage detection device 100according to the conventional mode) illustrated in FIG. 3 , the voltagevalue of the output terminal 50C of the differential amplifier circuit50 is 854 mV when the temperature is 0° C., 878 mV when the temperatureis 50° C., and 899 mV when the temperature is 100° C. All of thesevoltage values are higher than the ideal voltage value of 750 mV.

In the voltage detection device 100 according to the conventional mode,the voltage value of the output terminal 50C of the differentialamplifier circuit 50 increases as the temperature increases. The rate ofchange in the voltage value of the output terminal 50C of thedifferential amplifier circuit 50 when the temperature changes from 0°C. to 100° C. is a value obtained by dividing 899 by 854 and isapproximately 1.053.

In the voltage detection device 100 according to the conventional mode,the difference between the voltage value of the output terminal 50C ofthe differential amplifier circuit 50 and the ideal voltage value is 104mV to 149 mV.

On the other hand, in the voltage detection device 10 (voltage detectiondevice 10 according to the first embodiment) illustrated in FIG. 2 , thevoltage value of the output terminal 50C of the differential amplifiercircuit 50 is 713 mV when the temperature is 0° C., 705 mV when thetemperature is 50° C., and 697 mV when the temperature is 100° C. All ofthese voltage values are lower than the ideal voltage value of 750 mV.

In the voltage detection device 10 according to the first embodiment,the voltage value of the output terminal 50C of the differentialamplifier circuit 50 decreases as the temperature increases. The rate ofchange in the voltage value of the output terminal 50C of thedifferential amplifier circuit 50 when the temperature changes from 0°C. to 100° C. is a value obtained by dividing 697 by 713 and isapproximately 0.978. Ideally, the voltage value of the output terminal50C of the differential amplifier circuit 50 does not change regardlessof the temperature. That is, the ideal value of the rate of change inthe voltage value is 1. The rate of change (approximately 0.978) in thevoltage value in the voltage detection device 10 according to the firstembodiment is smaller than the rate of change (approximately 1.053) inthe voltage value in the voltage detection device 100 according to theconventional mode. That is, the rate of change in the voltage value inthe voltage detection device 10 according to the first embodiment iscloser to the ideal value than the rate of change in the voltage valuein the voltage detection device 100 according to the conventional mode.This can also be seen from the fact that in FIG. 5 , the absolute valueof the slope of the characteristic of the voltage value of the voltagedetection device 10 according to the first embodiment is smaller thanthe absolute value of the slope of the characteristic of the voltagevalue of the voltage detection device 100 according to the conventionalmode.

In the voltage detection device 10 according to the first embodiment,the difference between the voltage value of the output terminal 50C ofthe differential amplifier circuit 50 and the ideal voltage value is 37mV to 53 mV, which is smaller than the difference (104 mV to 149 mV) inthe voltage detection device 100 according to the conventional mode.

According to the first embodiment, the one end portion 20A of theresistance unit 20 and the differential amplifier circuit 50 areconnected by the plurality of wiring portions 31 and 32. As a result, itis possible to detect a voltage in which the influence of theconfiguration of the wiring pattern of the resistance unit 20 and thetemperature is suppressed to be low.

According to the first embodiment, the wiring portions 31 and 41 extendfrom the one end R1A and the other end R1B of the resistance element R1,and the wiring portions 32 and 42 extend from the one end R7A and theother end R7B of the resistance element R7. Here, the resistanceelements R1 and R7 are two resistance elements farthest from each otheramong the plurality of resistance elements R1 to R7. In the firstembodiment, the influence of the wiring pattern can be suppressed to belower than in a configuration in which two resistance elements to whichthe wiring portions are connected are located closer to each other, andthus, the influence of uneven current flow due to the difference in theconfiguration of the pattern wiring connecting the resistance elementscan be reduced.

In the first embodiment, the first connection portion 30 includes thetwo wiring portions 31 and 32, and the second connection portion 40includes the two wiring portions 41 and 42. However, the number ofwiring portions included in the first connection portion 30 and thesecond connection portion 40 is not limited to two. For example, each ofthe first connection portion 30 and the second connection portion 40 mayinclude three wiring portions. In this case, the three wiring portionsincluded in the first connection portion 30 are connected to, forexample, one ends of the resistance elements R1, R4, and R7 in the oneend portion 20A of the resistance unit 20. In this case, the threewiring portions included in the second connection portion 40 areconnected to, for example, the other ends of the resistance elements R1,R4, and R7 in the other end portion 20B of the resistance unit 20.

In the first embodiment, the wiring portions of the first connectionportion 30 and the second connection portion 40 are both connected tothe resistance elements R1 and R7. That is, the wiring portion of thefirst connection portion 30 and the wiring portion of the secondconnection portion 40 are connected to the same resistance element.However, the wiring portion of the first connection portion 30 and thewiring portion of the second connection portion 40 may be connected todifferent resistance elements. For example, the wiring portion of thefirst connection portion 30 may be connected to one ends of theresistance elements R1 and R7, and the wiring portion of the secondconnection portion 40 may be connected to the other ends of theresistance elements R3 and R4. A part of the wiring portion of the firstconnection portion 30 and a part of the wiring portion of the secondconnection portion 40 may be disposed in the same resistance element,and the rest of the wiring portion of the first connection portion 30and the rest of the wiring portion of the second connection portion 40may be connected to different resistance elements. For example, thewiring portion of the first connection portion 30 may be connected toone ends of the resistance elements R1 and R7, and the wiring portion ofthe second connection portion 40 may be connected to the other ends ofthe resistance elements R1 and R5.

In the first embodiment, the first connection portion 30 and the secondconnection portion 40 include the same number of wiring portions.However, the first connection portion 30 and the second connectionportion 40 may include different numbers of wiring portions. Forexample, the first connection portion 30 may include two wiring portionsconnected to one ends of the resistance elements R2 and R6, and thesecond connection portion 40 may include three wiring portions connectedto the other ends of the resistance elements R1, R4, and R7. Further,for example, the first connection portion 30 may include four wiringportions connected to one ends of the resistance elements R1, R2, R6,and R7, and the second connection portion 40 may include three wiringportions connected to the other ends of the resistance elements R2, R3,and R4.

Second Embodiment

FIG. 6 is a circuit diagram of a voltage detection device according to asecond embodiment of the present invention. The voltage detection device10 according to the second embodiment is different from the voltagedetection device 10 according to the first embodiment in that each ofthe first connection portion 30 and the second connection portion 40includes a wiring portion corresponding to each of the plurality ofresistance elements of the resistance unit 20.

As illustrated in FIG. 6 , the first connection portion 30 includes fourwiring portions 33 to 36, and the second connection portion 40 includesfour wiring portions 43 to 46.

One end portion 33A of the wiring portion 33 is connected to the one endR1A of the resistance element R1 in the one end portion 20A of theresistance unit 20. One end portion 34A of the wiring portion 34 isconnected to one end R2A of the resistance element R2 in the one endportion 20A of the resistance unit 20. One end portion 35A of the wiringportion 35 is connected to the one end R3A of the resistance element R3in the one end portion 20A of the resistance unit 20. One end portion36A of the wiring portion 36 is connected to the one end R4A of theresistance element R4 in the one end portion 20A of the resistance unit20. The other end portions 33B, 34B, 35B, and 36B of the wiring portions33, 34, 35, and 36 are connected to the input terminal 50B of thedifferential amplifier circuit 50. In this case, the input terminal 50Bcorresponds to the first input terminal.

A resistance element R33 is disposed in the wiring portion 33. Aresistance element R34 is disposed in the wiring portion 34. Aresistance element R35 is disposed in the wiring portion 35. Aresistance element R36 is disposed in the wiring portion 36. In thesecond embodiment, the resistance value of each of the resistanceelements R33 to R36 is 1Ω similarly to the resistance elements R31 andR32 of the first embodiment, but is not limited to 1 Ω.

One end portion 43A of the wiring portion 43 is connected to the otherend R1B of the resistance element R1 in the other end portion 20B of theresistance unit 20. One end portion 44A of the wiring portion 44 isconnected to the other end R2B of the resistance element R2 in the otherend portion 20B of the resistance unit 20. One end portion 45A of thewiring portion 45 is connected to the other end R3B of the resistanceelement R3 in the other end portion 20B of the resistance unit 20. Oneend portion 46A of the wiring portion 46 is connected to the other endR4B of the resistance element R4 in the other end portion 20B of theresistance unit 20. The other end portions 43B, 44B, 45B, and 46B of thewiring portions 43, 44, 45, and 46 are connected to the input terminal50A of the differential amplifier circuit 50. In this case, the inputterminal 50A corresponds to the second input terminal.

A resistance element R43 is disposed in the wiring portion 43. Aresistance element R44 is disposed in the wiring portion 44. Aresistance element R45 is disposed in the wiring portion 45. Aresistance element R46 is disposed in the wiring portion 46. In thesecond embodiment, the resistance value of each of the resistanceelements R43 to R46 is 1Ω similarly to the resistance elements R41 andR42 of the first embodiment, but is not limited to 1 Ω.

As described above, in the second embodiment, each of the wiringportions 33 to 36 of the first connection portion 30 connects one end ofeach of the plurality of resistance elements R1 to R4 of the resistanceunit 20 in the one end portion 20A of the resistance unit 20 and theinput terminal 50B of the differential amplifier circuit 50. Inaddition, each of the wiring portions 43 to 46 of the second connectionportion 40 connects the other end of each of the plurality of resistanceelements R1 to R4 of the resistance unit 20 in the other end portion 20Bof the resistance unit 20 and the input terminal 50A.

Hereinafter, a simulation result of the voltage detection device 10according to the second embodiment of the present invention will bedescribed. As the voltage detection device 10 according to the secondembodiment of the present invention, a voltage detection device 10illustrated in FIG. 6 is used. In the description, the simulation resultof the voltage detection device 10 according to the second embodiment ofthe present invention is compared with the voltage detection device 10according to the first embodiment of the present invention (see FIG. 4 )and the voltage detection device 100 according to the conventional mode(see FIG. 5 ).

The simulation in the second embodiment was performed similarly to thesimulation in the first embodiment. That is, a current of 1 A was passedfrom the power supply 60 to the voltage detection device 10, and thevoltage of the output terminal 50C of the differential amplifier circuit50 at that time was measured. In addition, simulation was performed foreach case where the temperature around the voltage detection device 10was 0° C., 50° C., and 100° C. Further, in the simulation, thedifference in temperature was represented by the difference inresistance values of the resistance elements Rp1 to Rp6.

The results of the simulation are shown in FIG. 7 and FIG. 8 . FIG. 7 isa table showing simulation results of the second embodiment. FIG. 8 is agraph showing the simulation results of the second embodiment.

FIG. 7 and FIG. 8 show the voltage value of the output terminal 50C ofthe differential amplifier circuit 50 and the ideal voltage value of theoutput terminal 50C of the differential amplifier circuit 50 in thevoltage detection device 10 illustrated in FIG. 6 for each temperatureof 0° C., 50° C., and 100° C. In FIG. 7 and FIG. 8 , the voltage valueof the voltage detection device 10 (voltage detection device 10according to the first embodiment of the present invention) illustratedin FIG. 2 and the voltage value of the voltage detection device 10(voltage detection device 100 according to the conventional mode)illustrated in FIG. 3 are shown for each temperature of 0° C., 50° C.,and 100° C.

As described in the simulation of the first embodiment, the idealvoltage value is 750 mV regardless of the temperature (see FIG. 4 andFIG. 5 ).

As shown in FIG. 7 and FIG. 8 , in the voltage detection device 100(voltage detection device 100 according to the conventional mode)illustrated in FIG. 3 , the voltage value of the output terminal 50C ofthe differential amplifier circuit 50 is 854 mV when the temperature is0° C., 878 mV when the temperature is 50° C., and 899 mV when thetemperature is 100° C.

In the voltage detection device 100 according to the conventional mode,the rate of change in the voltage value of the output terminal 50C ofthe differential amplifier circuit 50 when the temperature changes from0° C. to 100° C. is approximately 1.053.

In the voltage detection device 100 according to the conventional mode,the difference between the voltage value of the output terminal 50C ofthe differential amplifier circuit 50 and the ideal voltage value is 104mV to 149 mV.

In addition, in the voltage detection device 10 (voltage detectiondevice 10 according to the first embodiment of the present invention)illustrated in FIG. 2 , the voltage value of the output terminal 50C ofthe differential amplifier circuit 50 is 713 mV when the temperature is0° C., 705 mV when the temperature is 50° C., and 697 mV when thetemperature is 100° C.

In the voltage detection device 10 according to the first embodiment,the rate of change in the voltage value of the output terminal 50C ofthe differential amplifier circuit 50 when the temperature changes from0° C. to 100° C. is approximately 0.978.

In the voltage detection device 10 according to the first embodiment,the difference between the voltage value of the output terminal 50C ofthe differential amplifier circuit 50 and the ideal voltage value is 37mV to 53 mV.

On the other hand, in the voltage detection device 10 (voltage detectiondevice 10 according to the second embodiment) illustrated in FIG. 6 ,the voltage value of the output terminal 50C of the differentialamplifier circuit 50 is 749.8 mV regardless of the temperature. All ofthese voltage values are lower than the ideal voltage value of 750 mV.

In the voltage detection device 10 according to the second embodiment,the voltage value of the output terminal 50C of the differentialamplifier circuit 50 is the same regardless of the temperature. That is,in this simulation, the rate of change in the voltage value of theoutput terminal 50C of the differential amplifier circuit 50 in thevoltage detection device 10 according to the second embodiment is 1,similarly to the rate of change in the ideal voltage value. That is, therate of change in the voltage value in the voltage detection device 10according to the second embodiment is closer to the rate of change inthe ideal voltage value than the rate of change in the voltage value inthe voltage detection device 100 according to the conventional mode(approximately 1.053) and the rate of change in the voltage value in thevoltage detection device 10 according to the first embodiment(approximately 0.978).

In the voltage detection device 10 according to the second embodiment,the difference between the voltage value of the output terminal 50C ofthe differential amplifier circuit 50 and the ideal voltage value is 0.2mV, which is smaller than the difference (104 mV to 149 mV) in thevoltage detection device 100 according to the conventional mode and thedifference (37 mV to 53 mV) in the voltage detection device 10 accordingto the first embodiment.

According to the second embodiment, the wiring portions 31 to 34 and 41to 44 extend from all the resistance elements R1 to R4 of the resistanceunit 20. In the second embodiment, it is possible to detect a voltage inwhich the influence of the configuration of the wiring pattern of theresistance unit 20 and the temperature is suppressed to be lower than ina configuration in which the wiring portion extends from some resistanceelements in the resistance unit 20.

Third Embodiment

FIG. 9 is a circuit diagram of a voltage detection device according to athird embodiment of the present invention. The voltage detection device10 according to the third embodiment is different from the voltagedetection device 10 according to the first embodiment in the followingtwo points. The first difference is that one ends of some wiringportions among the plurality of wiring portions of the first connectionportion 30 are connected to portions other than the resistance elementsof the resistance unit 20, and the other ends of some wiring portionsamong the plurality of wiring portions of the second connection portion40 are connected to portions other than the resistance elements of theresistance unit 20. The second difference is that one end portions ofthe plurality of wiring portions of the first connection portion 30 arelocated at equal intervals in the extending direction of the one endportion 20A of the resistance unit 20, and one end portions of theplurality of wiring portions of the second connection portion 40 arelocated at equal intervals in the extending direction of the other endportion 20B of the resistance unit 20.

As illustrated in FIG. 9 , the first connection portion 30 includes sixwiring portions 30 a to 30 f, and the second connection portion 40includes six wiring portions 40 a to 40 f.

One end portion of the wiring portion 30 a is connected to a firstposition 20Aa in the one end portion 20A of the resistance unit 20. Oneend portion of the wiring portion 30 b is connected to a second position20Ab in the one end portion 20A of the resistance unit 20. One endportion of the wiring portion 30 c is connected to a third position 20Acin the one end portion 20A of the resistance unit 20. One end portion ofthe wiring portion 30 d is connected to a fourth position 20Ad in theone end portion 20A of the resistance unit 20. One end portion of thewiring portion 30 e is connected to a fifth position 20Ae in the one endportion 20A of the resistance unit 20. One end portion of the wiringportion 30 f is connected to a sixth position 20Af in the one endportion 20A of the resistance unit 20. The first position 20Aa to thesixth position Af are examples of a plurality of positions of the firstconnection portion. The other end portion of each of the wiring portions30 a to 30 f is connected to the input terminal 50A of the differentialamplifier circuit 50.

One end portion of the wiring portion 40 a is connected to a seventhposition 20Ba in the other end portion 20B of the resistance unit 20.One end portion of the wiring portion 40 b is connected to an eighthposition 20Bb in the other end portion 20B of the resistance unit 20.One end portion of the wiring portion 40 c is connected to a ninthposition 20Bc in the other end portion 20B of the resistance unit 20.One end portion of the wiring portion 40 d is connected to a tenthposition 20Bd in the other end portion 20B of the resistance unit 20.One end portion of the wiring portion 40 e is connected to an eleventhposition 20Be in the other end portion 20B of the resistance unit 20.One end portion of the wiring portion 40 f is connected to a twelfthposition 20Bf in the other end portion 20B of the resistance unit 20.The seventh position 20Ba to the twelfth position Bf are examples of aplurality of positions of the second connection portion. The other endportion of each of the wiring portions 40 a to 40 f is connected to theinput terminal 50B of the differential amplifier circuit 50.

Similarly, to the first embodiment and the second embodiment, theresistance element R is disposed in each of the wiring portions 30 a to30 f and 40 a to 40 f. In the third embodiment, the resistance value ofeach resistance element R is 1 Ω.

One ends of the resistance elements R1 to R7 are connected in a state ofbeing aligned in the extending direction at the one end portion 20A ofthe resistance unit 20. In addition, the other ends of the resistanceelements R1 to R7 are connected in a state of being aligned in theextending direction at the other end portion 20B of the resistance unit20. That is, the one end portion 20A of the resistance unit 20 extendsalong the extending direction, and the other end portion 20B of theresistance unit 20 extends along the extending direction. The extendingdirection is a direction in which the pattern wiring constituting theone end portion 20A and the other end portion 20B of the resistance unit20 extends. The extending direction of the one end portion 20A of theresistance unit 20 is an example of a first direction. The extendingdirection of the other end portion 20B of the resistance unit 20 is anexample of a second direction. In the third embodiment, both theextending direction of the one end portion 20A of the resistance unit 20and the extending direction of the other end portion 20B of theresistance unit 20 are the vertical direction in the plane of drawing ofFIG. 9 , but the present invention is not limited thereto. For example,when the pattern wiring constituting the one end portion 20A of theresistance unit 20 is bent, the extending direction of the one endportion 20A of the resistance unit 20 is also a bent direction. In FIG.9 , the extending direction of the one end portion 20A of the resistanceunit 20 and the extending direction of the other end portion 20B of theresistance unit 20 are the same direction but may be differentdirections.

The first position 20Aa to the sixth position 20Af are located at equalintervals in the extending direction of the one end portion 20A of theresistance unit 20. Specifically, in the extending direction of the oneend portion 20A of the resistance unit 20, a distance D1 between thefirst position 20Aa and the second position 20Ab, a distance D2 betweenthe second position 20Ab and the third position 20Ac, a distance D3between the third position 20Ac and the fourth position 20Ad, a distanceD4 between the fourth position 20Ad and the fifth position 20Ae, and adistance D5 between the fifth position 20Ae and the sixth position 20Afare equal distances.

The seventh position 20Ba to the twelfth position 20Bf are located atequal intervals in the extending direction of the other end portion 20Bof the resistance unit 20. Specifically, in the extending direction ofthe other end portion 20B of the resistance unit 20, a distance D6between the seventh position 20Ba and the eighth position 20Bb, adistance D7 between the eighth position 20Bb and the ninth position20Bc, a distance D8 between the ninth position 20Bc and the tenthposition 20Bd, a distance D9 between the tenth position 20Bd and theeleventh position 20Be, and a distance D10 between the eleventh position20Be and the twelfth position 20Bf are equal distances.

In FIG. 9 , the first position Aa is located at one end of theresistance element R1, and the sixth position Af is located at one endof the resistance element R7. On the other hand, the second position Abto the fifth position Ae are not located at one end of the resistanceelement. The second position Ab to the fifth position Ae are locatedbetween two adjacent resistance elements at the one end portion 20A ofthe resistance unit 20.

Note that the first position 20Aa to the sixth position Af are notlimited to the above positions on the condition that the distances D1 toD5 are equal distances. For example, all of the first position 20Aa tothe sixth position Af may be located between two adjacent resistanceelements in the one end portion 20A of the resistance unit 20 instead ofthe one end of the resistance element.

In FIG. 9 , the seventh position Ba is located at the other end of theresistance element R1, and the twelfth position Bf is located at theother end of the resistance element R7. On the other hand, the eighthposition Bb to the eleventh position Be are not located at the other endof the resistance element. The eighth position Bb to the eleventhposition Be are located between two adjacent resistance elements at theother end portion 20B of the resistance unit 20.

Similarly, to the first position 20Aa to the sixth position 20Af, theseventh position 20Ba to the twelfth position Bf are not limited to theabove positions on the condition that the distances D6 to D10 are equaldistances.

According to the third embodiment, similarly to the first embodiment andthe second embodiment, the one end portion 20A and the other end portion20B of the resistance unit 20 are connected to the differentialamplifier circuit 50 by the plurality of wirings. As a result, it ispossible to detect a voltage in which the influence of the configurationof the wiring pattern of the resistance unit 20 and the temperature issuppressed to be low.

Note that, by appropriately combining any embodiments among the variousembodiments described above, the effects of the respective embodimentscan be achieved.

Although the present invention has been sufficiently described inconnection with preferred embodiments with reference to the drawingsappropriately, various modifications and corrections are apparent tothose skilled in the art. Such modifications and corrections are to beunderstood as being included within the scope of the present inventionas set forth in the appended claims as long as they do not departtherefrom.

DESCRIPTION OF SYMBOLS

-   -   20 resistance unit    -   20A one end portion    -   30 first connection portion    -   31-36 wiring portion    -   40 second connection portion    -   41-46 wiring portion    -   50 differential amplifier circuit    -   50A input terminal    -   50B input terminal    -   R1-R7 resistance element    -   R31-R36 resistance element    -   R41-R46 resistance element

What is claimed is:
 1. A voltage detection device comprising: aresistance unit comprising a plurality of resistance elements connectedin parallel; a differential amplifier circuit; a first connectionportion that connects a plurality of positions different from each otherin one end portion of the resistance unit and a first input terminal ofthe differential amplifier circuit; and a second connection portion thatconnects a plurality of positions different from each other in the otherend portion of the resistance unit and a second input terminal of thedifferential amplifier circuit, wherein the voltage detection deviceconfigures to detect a voltage applied to the resistance unit based on avoltage of an output terminal of the differential amplifier circuit. 2.The voltage detection of claim 1, wherein the first connection portioncomprises: a first wiring portion that connects one end of a firstresistance element, which is one of the first resistance element and asecond resistance element located at positions farthest from each otheramong the plurality of resistance elements of the resistance unit, andthe first input terminal; and a second wiring portion that connects oneend of the second resistance element and the first input terminal, andthe second connection portion comprises: a third wiring portion thatconnects the other end of the first resistance element and the secondinput terminal; and a fourth wiring portion connecting the other end ofthe second resistance element and the second input terminal.
 3. Thevoltage detection of claim 1, wherein the first connection portionconnects one end of each of the plurality of resistance elements and thefirst input terminal, and the second connection portion connects theother end of each of the plurality of resistance elements and the secondinput terminal.
 4. The voltage detection of claim 1, wherein one ends ofthe plurality of resistance elements are connected in a state of beingaligned in a first direction at the one end portion of the resistanceunit, a plurality of positions of the first connection portion arelocated at equal intervals in the first direction, the other ends of theplurality of resistance elements are connected in a state of beingaligned in a second direction at the other end portion of the resistanceunit, and a plurality of positions of the second connection portion arelocated at equal intervals in the second direction.